OM4016 08/07 Maintenance - Section 4 Lubrication and Service Page 4-21 BRAKE CIRCUIT CHECKOUT AND ADJUSTMENT CHECKING FRONT BRAKE PAD WEAR NOTE: This check is nominally specified for every 500 hours of truck operation. If truck is operated in a very abrasive environment (i.e. sandy conditions), perform this check every 250 hours of truck operation, or more frequently, if conditions require it. 1. Stop the machine on level ground, apply the parking brake, and put blocks under the tires. 2. Remove any dirt/mud accumulation from all pads, calipers, and discs. 3.
Check disc pad (1, Figure 4-9) visually, and if the pad has reached the wear limit line (2) or if disc material thickness is less than 3 mm (0.12 in.), replace the pad. The pad wear may not be the same for both left and right wheels, so check the wear of all pads. FIGURE 4-9. FRONT PAD WEAR 1. Brake Pad 2. Wear Limit Line If any pad is worn beyond the limits stated above, replace all pads (both left and right sides). Refer to Shop Manual, Section "J", Brake Sys- tem, for specific disassembly, repair, or replace- ment procedures for the front brake assembly. Do not continue to use pads worn beyond limits. Worn pads may result in inadequate braking power. TESTING BRAKE PRESSURE 1.
Raise the air pressure to 8.3 kg/cm 2 (118 psi) pressure. 2. Remove the top air bleed plug (1, Figure 4-10) and install a 400 kg/cm 2 (5690 psi) pressure gauge. 3. Measure the hydraulic pressure when the brake pedal is depressed. Minimum pressure should be 187 kg/cm 2 (2660 psi). 4. Remove gauge and install plug. Refer to "Brake Bleeding", this section and bleed air from the calipers. FIGURE 4-10. FRONT BRAKE PRESSURE 1. Air Bleed Plugs 2. Brake Line